FRIDAY, March 1 (HealthDay News) --
Post-traumatic stress disorder, a form of anxiety disorder common among war veterans, was also frequently seen among intensive care patients put on a ventilator, a new study shows.

Some patients showed significant effects of the condition, also known as PTSD, up to two years later, the researchers found.

"We usually think of PTSD as something you develop if you go to war, are sexually assaulted or suffer a similar emotional trauma," senior study author, Dr. Dale Needham, a critical care specialist at the Johns Hopkins University School of Medicine, said in a Hopkins news release. "Instead, it may be as common, or more common, in ICU patients as in soldiers, but it's something many doctors including psychiatrists don't fully appreciate."

The researchers followed 520 ICU patients put on ventilators because of acute lung injury, which involves fluid in the lungs and multi-organ failure. The patients were treated at 13 different Baltimore ICUs over the course of three years.

The researchers had at least one visit with 186 of the ICU survivors during a two-year follow up period. The study revealed that 35 percent of these patients had significant symptoms of PTSD. Onset of these symptoms was greatest during the first three months after their hospital stay.

"Physical weakness usually gets better, but these mental symptoms often just linger," Dr. O. Joseph Bienvenu, an associate professor of psychiatry and behavioral sciences at Johns Hopkins, said in the news release. "We need to pay more attention to preventing and treating PTSD in these patients."

Former ICU patients with PTSD often have flashback and delusions about what happened while they were in the hospital, the researchers found. When medicated with sedatives and other narcotics, these patients may have memories of events that never actually happened.

"One woman thought her husband and the nurse were plotting to kill her," Bienvenu noted.

PTSD can also cause people to feel numb or detached. They can also be irritable, easily startled and have trouble sleeping. PTSD can affect people's quality of life and prevent them from doing their job or going about their normal daily routine.

Of the survivors who developed PTSD, 62 percent still had symptoms of the condition at their two-year visit and half were taking psychiatric drugs to treat their symptoms. Meanwhile, 40 percent of the patients with PTSD saw a psychiatrist within two years of their stay in the ICU.

Patients with PTSD who were depressed before they were put on a ventilator in the ICU were twice as likely to develop the condition. The longer the patients remained in the ICU, the more likely they were to develop PTSD symptoms.

Patients who developed sepsis (a severe response to infection), or were treated with high doses of opiates during their ICU stay, were also at greater risk for developing symptoms of PTSD.

Why ICU patients develop this condition remain unclear. The researchers suggested that inflammation, which can cause a breakdown in the blood-brain barrier, may change how the brain is affected by drugs commonly prescribed in the ICU.

Patients in the ICU with risk factors for PTSD should be informed about the condition, the researcher concluded. Other studies have shown that ICU diaries, in which nurses and family members record daily events during patients' treatment, can ease their PTSD symptoms and help them make better sense of their memories.

Each year, nearly 1 million patients in the United States are put on ventilators in an ICU and 200,000 develop acute lung injury.